The present invention relates to a liquid meter with a single jet, of the type comprising a motor member such as a turbine transmitting its movement to a totalizer by means of a transmission mechanism constituted by an axle whose one end is secured in rotation to the turbine and whose other end is engaged through an opening provided in the partition of a housing enclosing a gear train and a drive axle of the totalizer, said end comprising a pinion coacting with a pinion carried by the drive axle of the totalizer.
Such a liquid meter comprising a motor member disposed on the axis of movement of the liquid stream to be measured, such as a turbine, is called a xe2x80x9csingle jetxe2x80x9d because the liquid which passes through it and whose volume it measures, strikes this turbine with a single jet. As a result, the turbine is disposed in a region of passage of the liquid, called the measuring chamber, in which strong turbulence prevails because of the movement of the liquid jet and the agitation of the blades of said turbine, in particular the liquid having a rotating movement.
Conventionally, the totalizer actuates an indicator generally comprised by numerical drums, for demultiplication by a gear train.
The pinions of the gear train permitting transmission of the rotation of the turbine to the totalizer, are disposed in a housing and hence in a so-called immersed region, the liquid passing through the opening of the partition of the housing. The pinions are however isolated from the turbulence region of the measuring chamber by the partition of the housing and are accordingly in a region exempt from turbulence.
The liquid whose volume is measured can entrain solid particles. In the case of water, these solid particles can be abrasive, such as sand. The turbulence of the liquid in the turbine agitates the particles which are maintained in suspension in said liquid and it is noted that the turbulence is generally sufficiently strong to cause the entry of the solid particles into the chamber of the housing enclosing the transmission mechanism and in particular the pinions, the solid particles passing through the opening provided in the partition for the passage of the axle of the turbine, although this orifice is in a raised position above the turbine.
As a result, the solid particles move beyond the partition into the chamber containing the pinions and, as there is practically no longer any turbulence in this chamber, the solid particles settle. Because of this, the solid particles fall under the influence of gravity and come to rest particularly in the teeth of the pinions, which gives rise to deterioration of said pinions changing the transmission of the rotation of the turbine to the totalizer and as a result the precision of the meter.
From GB-A-746, there is known a water meter in which the water enters a chamber from one side so as to strike a section of the circumference of a turbine in one or two flows, which gives rise to a load on a single side of the turbine. The moving current causes rotary movement in the chamber and deflects the axis of turbulence toward the still water chamber. Also, so as to protect the axle of the turbine against the pressure of the flow of water and to space the flow from the center of the turbine, there has been proposed a semicircular partition at least in part surrounding the axle to deflect the water current so as to concentrate the flow only on the blades of the turbine. This partition can extend entirely about the axle of the turbine above and below the blades. Because of this, the lower partition, when it totally surrounds the axle, can constitute a receptacle for solid particles which are enclosed therein as in a trap and risk sooner or later blocking the turbine. Similarly, the space between the upper partition and the axle of the turbine is nowhere mentioned as being arranged to avoid an accumulation of solid particles. In particular, even if the solid particles were prevented from passing toward the pinion chamber, by the form described in this patent, the axle having an upper portion forming a retaining edge on which said particles could deposit, there would be an accumulation of said solid particles about said axle. Such a meter accordingly promotes the retention of solid particles.
The present invention therefore has for its object to provide a liquid meter with a single jet, in which the pinions of the transmission mechanism are protected against deterioration due to solid abrasive particles that can be contained in the measured liquid.
To this end, the present invention has for its object a liquid meter with a single jet, of the type comprising a motor member such as a turbine transmitting its movement to a totalizer by means of a transmission mechanism constituted by an axle whose one end is secured in rotation to the motor member and whose other end is engaged in the chamber provided in the housing enclosing a gear train, and a drive axle for the totalizer, through an opening provided in the partition of said housing, said end comprising a pinion coacting with a pinion mounted on the drive axle of the totalizer, comprising means for protecting said axle, characterized in that said protection means are arranged to prevent the passage of solid particles contained in the liquid through the opening provided in the partition of the housing toward the chamber enclosing the transmission mechanism, by defining a protected region of least turbulence surrounding said axle adjacent the opening (5) and promoting the falling back, under the influence of their gravity, of said particles, which lose their initial kinetic energy during their passage toward the opening of the partition.
Thus, preferably, the protection means permit avoiding the presence of solid particles in the immersed chamber of the housing enclosing the transmission mechanism, such that the latter is protected against deterioration, in particular from the deposit of these particles on the pinions, in particular at the level of the teeth, of the pinion chain of said transmission mechanism.
The life of the liquid meter with a single jet is thus prolonged by guaranteeing it moreover a greater reliability as to the precision of the measurements that are carried out.
Preferably, the totalizer is out of the water, which is to say that it is carried by the housing and separated from the latter by at least one partition. Preferably, the drive axle of said totalizer of the transmission mechanism drives in rotation an axle of the totalizer by magnetic transmission through the partition, said drive axle comprising, at its end opposite that carrying the pinion coacting with the pinion carried by the motor member axle, at least one magnet coupled to a magnet mounted on the axle of the totalizer.
Said means therefore define a region of least turbulence in the measuring chamber of the meter surrounding the axle of the transmission mechanism connected to the motor member and particles in said region are no longer subject to the influence of the turbulence of the liquid prevailing in the measuring chamber in which is disposed the turbine. The particles lose their initial kinetic energy even if the latter were relatively high so as to fall under the influence of gravity outside this region in the turbulence region in which they are carried by the liquid flow.
Preferably, said protection means are constituted by a cylindrical skirt arranged at the periphery of the opening of the partition of the housing, projecting toward the motor member, and entirely surrounding said axle so as to delimit the protected region of least turbulence substantially on the assembly of the length of said axle between the motor member and the partition of the housing.
Preferably, the internal surface of the skirt has at least one longitudinal radially projecting rib further promoting the braking of the rotative movement of the liquid within the skirt, which permits further decreasing the residual speed of the particles.
Preferably, the turbine acting as the motor member has a hub secured to the turbine at its upper portion fixed to the turbine and in which the axle is fixed in rotation, said hub extending from the turbine to the opening of the partition and having preferably a cross-section that enlarges from the opening of the partition toward the turbine, at least facing the skirt. This particular shape of the hub defines with the cylindrical skirt a region of least turbulence whose form promotes the fall of particles which thus do not encounter any retention place in said region. Preferably, the hub is of conical shape.